Unless the wing can be extended fully, it may not be able to withstand the loading put on the platform when the orbiter docks.

The panel had to be lashed together where it had come apart

Nasa officials say the 35m (115ft) wing probably snagged on a guidewire, or guidewire support, as it was being unfurled.

The next shuttle, due in December, is supposed to deliver Europe's main contribution to the ISS project - its Columbus laboratory.

Failure to sort the solar panel problem would have left Nasa no choice but to delay the December flight, keeping the already much-delayed Columbus sitting on the ground even longer.

The ISS is currently being visited by space shuttle Discovery. Astronauts from the orbiter have already attached the new Harmony module to a temporary location on the station. The unit will be moved into a permanent site once the orbiter has left.

Harmony will act as a passageway between three science laboratories: The existing US Destiny lab, and the soon-to-launch European Columbus and Japanese Kibo experimental units.